JP2006318840A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a discharge lamp lighting device smaller in size and reduce a number of components and a cost by using a transformer which has a electric conductive property and is used for generating a start-up signal. <P>SOLUTION: A transformer 7 having an electric transfer function to a discharge lamp as well as a start-up function for supplying a start-up signal to the discharge lamp is composed of closed magnetic circuit cores (15, 16) made of a magnetic material, a first winding wire 7p and a second winding wire 7s and an auxiliary winding wire 7v provided for supplying a voltage necessary for generating a start-up signal to a start-up circuit. The first winding wire 7p and the second winding wire 7s are wound around a common core column 15a as a center and the auxiliary winding wire 7v is wound around another core column 15b. A start-up signal is generated, based on the voltage supplied from the auxiliary winding wire 7v and is impressed to the discharge lamp through the main winding wires (7p, 7s). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for realizing a discharge lamp lighting device suitable for downsizing and reduction of the number of parts and cost.

  It is known that a lighting circuit for a discharge lamp such as a metal halide lamp used for an illumination light source for a vehicle has a DC booster circuit having a DC-DC converter configuration, a DC-AC converter circuit, and a starting circuit. Yes. For example, the DC input voltage from the battery is converted to the desired voltage in the DC booster circuit, then converted to AC output by the DC-AC converter circuit in the subsequent stage, and the start signal is superimposed on this and supplied to the discharge lamp (For example, refer to Patent Document 1). For example, a switching regulator using a transformer or the like is used for the DC booster circuit, and a dedicated transformer is used for the start signal generating circuit.

Japanese Utility Model Publication No. 6-13100

  By the way, the conventional lighting circuit requires a transformer for power transmission to the discharge lamp and a transformer for generating a starting pulse, and there are problems in terms of device size and cost. For example, when a discharge lamp is used as an automobile illumination light source, it is necessary to arrange a lighting circuit in a limited space (for example, when a lighting circuit unit is accommodated in a lamp).

  Therefore, the present invention has an object to achieve a reduction in the size of the discharge lamp lighting device and reduce the number of parts and cost by using a transformer having a power transmission function and used for generating a start signal. To do.

  The present invention provides a transformer having a power transmission function to a discharge lamp and a start function for supplying a start signal to the discharge lamp, and receives a DC input voltage to perform AC conversion and outputs the output of the transformer to the discharge lamp. A discharge lamp lighting device including a DC-AC conversion circuit to be supplied and a start circuit for applying a start signal to the discharge lamp has the following configuration.

  In order for the transformer to supply a start circuit with a closed magnetic circuit type core formed of a magnetic material, a main winding including a primary winding and a secondary winding, and a voltage necessary for generating a start signal. Having auxiliary windings provided.

  ・ The primary and secondary windings are wound around the common core strut, and the auxiliary winding is different from the core strut around which the primary and secondary windings are wound. It is wound around the core support.

  A starting signal is generated by the starting circuit based on the voltage supplied from the auxiliary winding and applied to the discharge lamp via the main winding.

  Therefore, in the present invention, by using one transformer for power transmission to the discharge lamp and application of a start signal to the discharge lamp, it is effective for simplification and miniaturization of the circuit configuration. And about the primary winding and the secondary winding which constitute the main winding, the magnetic coupling can be strengthened by winding it around the same core strut, and for the auxiliary winding, the main winding and Can be wound around another core column to weaken the magnetic coupling with the main winding.

  According to the present invention, the discharge lamp lighting device can be reduced in size, and the number of parts and cost can be reduced. For example, when a discharge lamp is used as a light source for an automobile, it is effective for application to a lighting device of a resonance type high frequency lighting system (the supply voltage to the starting circuit is reduced without using a converter transformer or the like in the primary circuit of the transformer). Obtainable.). Then, by weakening the magnetic coupling between the auxiliary winding and the main winding, it is possible to reduce the influence of the high voltage induced in the auxiliary winding when the start signal is generated. In addition, it is more effective in reducing core loss and the like than a configuration in which an auxiliary winding is added to a resonance coil.

  As a transformer structure for weakening the magnetic coupling between the auxiliary winding and the main winding, in the closed magnetic circuit type configuration using the E-type core or the U-type core, the main winding is provided on the straight portion of the first core column. It is preferable that the wire is wound and the auxiliary winding is wound around the straight portion of the second core column.

  FIG. 1 shows an example of the basic configuration of a discharge lamp lighting device according to the present invention. The discharge lamp lighting device 1 has a DC-AC conversion circuit 3 that receives power supply from a DC power source 2 and a starting circuit in the circuit configuration. 4 is provided.

  The DC-AC conversion circuit 3 is provided for receiving a DC input voltage (see “+ B” in the figure) from the DC power supply 2 and performing AC conversion and boosting. In this example, two switching elements 5H and 5L and a control means 6 for controlling driving of these elements are provided. In other words, one end of the switching element 5H on the higher stage side is connected to the power supply terminal, and the other end of the switching element is grounded via the switching element 5L on the lower stage side. Alternately on / off. In the figure, the elements 5H and 5L are indicated by switch symbols for simplification, but semiconductor switching elements such as field effect transistors (FETs) and bipolar transistors are used.

  The DC-AC conversion circuit 3 has a series resonance circuit including an inductance element or a transformer and a capacitor. In this example, the DC-AC conversion circuit 3 has a transformer 7 for power transmission, and a circuit configuration using a resonance phenomenon between a resonance capacitor 8 and an inductor or an inductance component is used on the primary side. Yes. That is, as a configuration form, for example, there are the following three types.

(I) Form using resonance between resonance capacitor 8 and inductance element (II) Form using resonance between resonance capacitor 8 and leakage (leakage) inductance of transformer 7 (III) Resonance capacitor 8 and inductance A form using resonance with the leakage inductance of the element and the transformer 7.

  First, in the above (I), an inductance element 9 such as a resonance coil is provided, for example, one end of the element is connected to the resonance capacitor 8, and the capacitor 8 is used as a connection point between the switching elements 5H and 5L. Connecting. And the structure which connected the other end of the inductance element 9 to the primary winding 7p of the transformer 7 is mentioned.

  In (II) above, the use of the inductance component of the transformer 7 eliminates the need to add a resonance coil or the like. That is, one end of the resonance capacitor 8 may be connected to the connection point between the switching elements 5H and 5L, and the other end of the capacitor 8 may be connected to the primary winding 7p of the transformer 7.

  In the above (III), a series combined reactance of the inductance element 9 and the leakage inductance can be used.

  In any form, the series resonance of the resonance capacitor 8 and the inductive element (inductance component or inductance element) is used, and the driving frequency of the switching elements 5H and 5L is defined to a value equal to or higher than the series resonance frequency. By alternately turning on / off, the discharge lamp 10 (such as a metal halide lamp used in a vehicular lamp) connected to the secondary winding 7s of the transformer 7 can be sine wave-lit. In the drive control of each switching element by the control means 6, it is necessary to drive each element reciprocally so that both switching elements are not turned on (depending on on-duty control or the like). As for the series resonance frequency, the resonance frequency before lighting is indicated as “f1”, the resonance frequency in the lighting state as “f2”, the capacitance of the resonance capacitor 8 as “Cr”, and the inductance of the inductance element 9 as the inductance. When the primary inductance of the transformer 7 is denoted as “Lp1”, for example, in the above-described form (III), “f1 = 1 / (2 · π · √ (Cr · (Lr + Lp1) before the discharge lamp is turned on. For example, if the drive frequency is lower than f1, the loss of the switching element is increased and the efficiency is deteriorated, so that the switching operation is performed in a frequency region higher than f1. “F2≈1 / (2 · π · √ (Cr · Lr))” (f1 <f2) Also in this case, the switching operation is performed in a frequency region higher than f2.

  The transformer 7 has a main winding 7M including a primary winding 7p and a secondary winding 7s, and an auxiliary winding 7v provided for generating a start signal to the discharge lamp 10.

  The start circuit 4 is provided to supply a start signal to the discharge lamp 10, and includes, for example, a capacitor 11, a switching element 12 (shown in a simplified manner by a switch symbol in the drawing), and a rectifier circuit 13. . The voltage obtained by the auxiliary winding 7v is supplied to the capacitor 11 via the rectifier circuit 13, and the switching element 12 becomes conductive when the terminal voltage of the capacitor exceeds a predetermined threshold value. At this time, a signal generated in the primary winding 7p of the transformer 7 is boosted by the transformer 7 and applied to the discharge lamp 10 (a start signal is superimposed on the AC converted output and supplied to the discharge lamp 10). .) In this example, one end of the self-breakdown switching element 12 is connected to the intermediate tap of the primary winding 7p.

  In the configuration of FIG. 1, the transformer 7 has both a power transmission function to the discharge lamp 10 and a start function for supplying a start signal to the discharge lamp 10. That is, the DC-AC conversion circuit 3 converts and boosts the DC input to AC under the control means 6 to control the power of the discharge lamp 10 and is supplied from the auxiliary winding 7v of the transformer 7. A starting signal is generated by the starting circuit 4 based on the voltage, and is applied to the discharge lamp via the main winding 7M of the transformer 7.

  For example, a configuration in which the primary voltage generation circuit 14 is provided for the capacitor 11 without using the auxiliary winding 7v as shown by a broken line and a two-dot chain line in FIG. As the circuit configuration, a DC input voltage “+ B” is received and a desired voltage can be obtained by a flyback type DC-DC converter. However, as the voltage rises as the capacitor 11 is charged after the boosting starts, the circuit increases. The problem is that the secondary current discharge time of the transformer (converter transformer) constituting the converter is shortened, and sufficient boosting cannot be performed. In other words, the discharge time of the secondary current is inversely proportional to the output voltage of the converter and becomes shorter as the voltage rises, and should be originally taken out to the secondary side due to the influence of the junction capacitance of the rectifying diode provided in the converter. Energy cannot be obtained, and sufficient boosting cannot be performed. Alternatively, it is necessary to increase the inductance of the converter transformer, which increases the size of the transformer and is accompanied by an influence on components such as a switching element, its control circuit, and a diode. Become.

  In addition to this, a method of obtaining a primary voltage necessary for starting the discharge lamp by using the inductance element 9 (resonance coil) or the secondary winding 7s may be considered, but an auxiliary winding is added to the resonance coil. In the configuration, the core becomes large, and thermal problems arise due to increased loss (∵core loss is proportional to the core volume). Alternatively, in the method using the secondary winding of the transformer, the signal is applied to the capacitor 11 when the starting signal that is a high voltage pulse is generated, and the attenuation of the pulse becomes a problem.

  Therefore, in the present invention, the auxiliary winding 7v is provided in the transformer 7, and a voltage necessary for generating the start signal is obtained and supplied from the rectifier circuit 13 of the start circuit 4 to the capacitor 11 as described above. Various problems can be avoided and miniaturization, compactness, and the like can be realized. For example, a converter transformer is not required in the primary voltage generation circuit in the starter circuit 4, which is suitable for simplifying the circuit configuration.

  Next, a configuration example of the transformer according to the present invention will be described.

  In the application of the present invention, the transformer has a closed magnetic circuit type configuration using an E-type core or a U-type core, and examples thereof include the following forms.

-A configuration combining two E-type cores-A configuration combining E-type cores and I-type cores-A configuration combining two U-type cores-A configuration combining U-type cores and I-type cores.

  That is, the magnetic circuit is closed around the magnetic core and the gap, and an open type configuration such as an I-type core is excluded.

  In the magnetic core, the main winding 7M is wound around the straight portion of the first core column, and the auxiliary winding 7v is wound around the straight portion of the second core column.

  2 to 4 illustrate a transformer 7 having a structure in which an E-type core and an I-type core are combined. FIG. 2 is a perspective view, and FIG. 3 is an exploded perspective view. FIG. 4 is a connection diagram inside the transformer.

  In FIG. 3, along the central axis of the first core support 15a, which is the middle leg of the E-type core 15, between the I-type core 16 and the primary winding 7p, the spacer 17, the secondary winding 7s, An insulating bobbin 18 and a terminal block 19 that also serves as a spacer are disposed, and a terminal block 20 is attached to the E-type core 15.

  In this example, a primary winding 7p is disposed on the outer periphery of the first core support 15a, an insulating bobbin 18 is disposed around the primary winding 7p, and a secondary winding 7s is wound around the outer periphery of the insulating bobbin 18. Has been. In the magnetic circuit using the E-type core 15 and the I-type core 16, a gap is formed between the core support 15 a and the I-type core 16.

  As shown in FIGS. 3 and 5, the primary winding 7 p is formed in a roll shape using a thin conductor and has a structure wound in a spiral shape when viewed from the direction along the central axis. For example, as shown in FIG. 5B, a pair of terminals 21 and 21 are provided in the primary winding 7p, and these terminals are in the winding direction of the primary winding 7p (in the drawing). Are formed at diagonal positions opposite to each other with respect to the arrow “R” direction). As a result, the primary current flows uniformly to the conductor portion of the primary winding 7p, and it is possible to prevent unevenness in the coupling with the secondary winding 7s.

  And the connection end 22 with the starting circuit 4 is formed in the primary winding 7p, for example, as shown with the broken line in FIG.5 (B), either one length extended in the winding direction of a primary winding The connection end 22 is integrally formed on the side. FIG. 3 shows the winding start end 21s, winding end 21e, and connection end 22 of the primary winding 7p, where 21s and 22 are formed in the same direction, and 21e is formed in the opposite direction.

  For the base material of the primary winding 7p, for example, a metal thin plate or a flexible film-like conductor (such as a flexible printed wiring board) can be used.

  The secondary winding 7s is formed in a coil shape using, for example, a conductive wire. Regarding the base material of the secondary winding 7s, the minimum necessary amount is achieved while suppressing copper loss by adopting a so-called edgewise winding (or flat winding) form in which a rectangular wire is used to be wound in an annular shape. A transformer can be configured with a limited size.

  Note that one end of the secondary winding 7s is a winding start end 23s, and the other end is a winding end 23e.

  The insulating bobbin 18 has a configuration in which a cylindrical portion 18a and a flange portion 18b are integrally formed, and the primary winding 7p is disposed in the hole of the cylindrical portion 18a.

  Moreover, the spacer 17 and the terminal block 19 are ring-shaped, and the terminal block 19 is provided with a terminal portion to which the winding end 21e of the primary winding 7p is connected. That is, the winding end 21 e of the primary winding 7 p is connected to an external circuit (not shown) via the terminal block 19.

  Thus, in order to make the magnetic coupling between the primary winding 7p and the secondary winding 7s as strong as possible for the main winding 7M, the primary winding 7p and the secondary winding 7s have a common core strut (main In the example, the middle leg 15a) is wound around the central axis 15a). That is, in this example, the configuration in which the primary winding is arranged on the outer periphery of the core support and the secondary winding is arranged on the outer periphery thereof is shown. However, the present invention is not limited to this, and the primary winding is not limited thereto. A configuration may be adopted in which the positional relationship between the wire and the secondary winding is reversed, the secondary winding is disposed on the outer periphery of the core column, and the primary winding is disposed on the outer periphery thereof.

  In FIG. 3, the auxiliary winding 7v is wound around the bobbin 24 using a conductive wire, one end of which is a winding start end 25s and the other end is a winding end 25e.

  The auxiliary winding 7v is disposed on the outer periphery of a core support 15b (in this example, an outer leg) different from the core support 15a around which the main winding 7M is wound. This is to weaken the magnetic coupling with the main winding 7M. That is, if the auxiliary winding 7v is arranged with the same degree of magnetic coupling as the main winding, a high voltage pulse equivalent to the starting signal generated when starting the discharge lamp is induced in the auxiliary winding 7v. Is absorbed by the capacitor 11 and energy necessary for generating the activation signal cannot be used effectively. Such a problem can be prevented by weakening the magnetic coupling between the main winding 7M and the auxiliary winding 7v.

  The U-shaped terminal block 20 is provided with a terminal portion to which the connection end 22 of the primary winding 7p is connected and a terminal portion to which the winding start end of each winding is connected. It is connected to an external circuit (not shown).

  As shown in FIG. 4, the winding start end 25s of the auxiliary winding 7v provided in the transformer 7, the winding start end 21s of the primary winding 7p, and the winding start end 23s of the secondary winding 7s are connected to each other (COMMON ) It is connected to the terminal.

  The symbol “·” in the figure indicates the start of winding, and in accordance with the polarity shown in the figure, by adjusting the polarity between the generated voltage of the secondary winding 7s and the generated voltage of the auxiliary winding 7v, the transformer The potential difference can be suppressed (contributes to simplification of the breakdown voltage structure). For example, when the voltage induced in the auxiliary winding at the time of generation of the start signal is 5 kV and the peak value of the secondary voltage accompanying the start signal is 25 kV, the difference voltage of 20 kV is A transformer having a dielectric strength is sufficient (in contrast, when the polarity is opposite to the above, a dielectric strength of 25 kV is required, which causes an increase in the size of the transformer structure, etc.).

  FIG. 6 shows an example of a circuit configuration using the above-described transformer. A starting signal is generated by the starting circuit 4 based on the voltage obtained by the auxiliary winding 7v, and this is transmitted via the main winding 7M of the transformer 7. Applied to the discharge lamp 10.

  The starter circuit 4 includes a capacitor 11, a switching element 12, and a rectifier circuit 13.

  In this example, one end of the capacitor 11 is connected to the connection terminal (22) of the primary winding 7p via a self-breakdown switching element 12 such as a spark gap. The other end of the capacitor 11 is grounded and connected to the common terminal of the transformer 7.

  The rectifier circuit 13 is configured using a diode 26 and a resistor 27, and the anode of the diode 26 is connected to one end (winding end) of the auxiliary winding 7 v, and the cathode of the diode is switched with the capacitor 11 via the resistor 27. A connection point with the element 12 is connected.

  When the capacitor 11 is charged from the auxiliary winding 7v through the diode 26 and the terminal voltage of the capacitor 11 exceeds the threshold value, the switching element 12 becomes conductive, and at this time, a high voltage pulse is generated. That is, when the voltage obtained by the auxiliary winding 7v is applied to the capacitor 11 via the diode 26 and the resistor 27, the terminal voltage of the capacitor rises, and the primary state of the transformer 7 when the switching element 12 becomes conductive. A signal generated in the winding 7p is applied to the discharge lamp 10 as a starting signal after being boosted by the transformer.

  This example is useful for simplifying the circuit configuration and reducing the cost.

  In addition, in the power control of the discharge lamp, when detecting the current flowing through the discharge lamp and the voltage applied to the discharge lamp, for example, a detection terminal is provided in the secondary winding, or a detection winding is provided on the secondary side of the transformer. Implementation with various configurations such as addition is possible.

It is a figure which shows the basic circuit structural example which concerns on this invention. It is a figure which shows the structural example of a transformer with FIG. 3, and this figure is a perspective view. It is a disassembled perspective view. It is a connection diagram in a transformer. It is a figure which shows the structural example of a primary winding. It is a figure which shows the circuit structural example of the principal part regarding generation | occurrence | production of the signal for starting.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Discharge lamp lighting device, 3 ... DC-AC conversion circuit, 4 ... Starting circuit, 7 ... Transformer, 7M ... Main winding, 7p ... Primary winding, 7s ... Secondary winding, 7v ... Auxiliary winding, 10 ... Discharge lamp, 15 ... Core, 15a ... First core support, 15b ... Second core support

Claims (2)

A transformer having a power transmission function to the discharge lamp and a starting function for supplying a start signal to the discharge lamp; and a DC--that receives the DC input voltage, performs AC conversion, and supplies the output of the transformer to the discharge lamp. In a discharge lamp lighting device provided with an AC conversion circuit and a start circuit for applying the start signal to the discharge lamp,
For the transformer to supply a closed magnetic circuit type core made of a magnetic material, a main winding including a primary winding and a secondary winding, and a voltage necessary for generating the starting signal to the starting circuit. And an auxiliary winding provided in the
The primary and secondary windings are wound around a common core support and the auxiliary winding is separate from the core support around which the primary and secondary windings are wound. The start signal is generated by the start circuit based on the voltage supplied from the auxiliary winding and applied to the discharge lamp via the main winding. A discharge lamp lighting device. In the discharge lamp lighting device according to claim 1,
The transformer is configured using an E-type core or a U-type core, the main winding is wound around the straight portion of the first core column, and the auxiliary winding is wound around the straight portion of the second core column. A discharge lamp lighting device characterized by being rotated.

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